// Tencent is pleased to support the open source community by making RapidJSON
// available.
//
// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All
// rights reserved.
//
// Licensed under the MIT License (the "License"); you may not use this file
// except in compliance with the License. You may obtain a copy of the License
// at
//
// http://opensource.org/licenses/MIT
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

#ifndef RAPIDJSON_MEMORYSTREAM_H_
#define RAPIDJSON_MEMORYSTREAM_H_

#include "stream.h"

#ifdef __clang__
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(unreachable - code)
RAPIDJSON_DIAG_OFF(missing - noreturn)
#endif

RAPIDJSON_NAMESPACE_BEGIN

//! Represents an in-memory input byte stream.
/*!
    This class is mainly for being wrapped by EncodedInputStream or
   AutoUTFInputStream.

    It is similar to FileReadBuffer but the source is an in-memory buffer
   instead of a file.

    Differences between MemoryStream and StringStream:
    1. StringStream has encoding but MemoryStream is a byte stream.
    2. MemoryStream needs size of the source buffer and the buffer don't need to
   be null terminated. StringStream assume null-terminated string as source.
    3. MemoryStream supports Peek4() for encoding detection. StringStream is
   specified with an encoding so it should not have Peek4(). \note implements
   Stream concept
*/
struct MemoryStream {
  typedef char Ch;  // byte

  MemoryStream(const Ch *src, size_t size)
      : src_(src), begin_(src), end_(src + size), size_(size) {}

  Ch Peek() const { return RAPIDJSON_UNLIKELY(src_ == end_) ? '\0' : *src_; }
  Ch Take() { return RAPIDJSON_UNLIKELY(src_ == end_) ? '\0' : *src_++; }
  size_t Tell() const { return static_cast<size_t>(src_ - begin_); }

  Ch *PutBegin() {
    RAPIDJSON_ASSERT(false);
    return 0;
  }
  void Put(Ch) { RAPIDJSON_ASSERT(false); }
  void Flush() { RAPIDJSON_ASSERT(false); }
  size_t PutEnd(Ch *) {
    RAPIDJSON_ASSERT(false);
    return 0;
  }

  // For encoding detection only.
  const Ch *Peek4() const { return Tell() + 4 <= size_ ? src_ : 0; }

  const Ch *src_;    //!< Current read position.
  const Ch *begin_;  //!< Original head of the string.
  const Ch *end_;    //!< End of stream.
  size_t size_;      //!< Size of the stream.
};

RAPIDJSON_NAMESPACE_END

#ifdef __clang__
RAPIDJSON_DIAG_POP
#endif

#endif  // RAPIDJSON_MEMORYBUFFER_H_
